Optical connector receptacle having switching capability

ABSTRACT

An optical fiber connector adapter has a sensing mechanism for determining when the adapter has a connector plug therein and when the adapter is vacant or empty. The sensing mechanism creates an indication of the state of the adapter which is transmitted to a control circuit. The control circuit responds to the indication by activating or de-activating a laser, for example, which applies optical energy to the adapter. The laser is deactivated when the adapter has no connector plug therein and is activated when there is a connector plug in place in the adapter. In two of the embodiments of the invention, the sensing mechanism signals the impending insertion or withdrawal of the connector plug relative to the adapter.

This application is a Continuation-In-Part of U.S. patent application Ser. No. 09/748,906, filed Dec. 27, 2000, of Norman R. Lampert et al.

FIELD OF THE INVENTION

This invention relates to optical connection adapters for use in fiber optical transmission and, more particularly, to an adapter for creating an electrical indication of the condition of the connector.

BACKGROUND OF THE INVENTION

Optical fiber transmission systems are becoming widely used in the transmission of signals such as data, voice and the like, and in many instances, are replacing traditional electrical systems. Many of the arrangements common to electrical systems, such as coupling, interconnection, splicing, and the like have their counterparts in optical systems but, because of the totally different characteristics of the transmission media, i.e., optical fiber versus metallic wire, connectorization, splicing, and the like involve quit a different apparatus. Where, for example, it is necessary to make a great number of connections in one location, both systems may use what is referred to in the art as patch panels, which provide arrays of connector adapters for interconnection, but the interconnections themselves are generally quite different.

It is common practice in the optical connector art to terminate a length of optical fiber with a connector, an example of which is the SC type connector that is shown and described in U.S. Pat. No. 5,212,752 of Stephenson et al. There are numerous types of such fiber terminating connectors, and, inasmuch as there has been little effort directed to standardization, each type of connector generally requires a different coupling arrangement to permit interconnection of two fibers, for example. The SC and LC connectors are becoming more and more popular, and the remainder of the discussion, in the interest of simplicity, is devoted to such connectors. It is to be understood that the following description of the principles and apparatus of the invention is applicable to other types of connectors as well. As is shown in the Stephenson et al. patent, an SC connector includes a ferrule assembly including a barrel having a collar at one end and an optical fiber terminating ferrule projecting from the barrel. The ferrule assembly is disposed in a plug frame such that an end portion of the ferrule projects from one end of the frame. The plug frame is configured to snap lock into a grip member having a locating key thereon, and the grip is inserted into one side of a slotted coupler adapter, with the locating key inserted into the slot. The grip of a corresponding SC connector is inserted into the other side of the adapter so that the ends of the ferrules abut each other to form a low insertion loss optical interconnection. In the SC connector, the ferrules are spring loaded longitudinally to insure contact between the fiber containing ferrule ends. The entire interconnect operation involves linear motion only and results in a low insertion loss, mechanically stable, protected junction between the two fibers. The expenditure of time in making the interconnection is small and the operator or installer is relieved of having to perform anything other than simple linear motion in plugging the connectors into the coupling adapter.

When large numbers of such interconnections are to be made, it is common practice to use patch panels for holding an array of a large number of coupler adapters. Thus, there can literally be hundreds of such adapters, all in close proximity to each other, mounted in the panel. As long as only a single type of connector, such as the SC connector, is involved, simple adapters may be used for plugging in the connectors from each side of the patch panel. In view of the fact that there are several different types of connectors in widespread use today, it has become common practice to replace the simple adapters with buildout blocks or buildout coupling adapters. In U.S. Pat. No. 5,274,729 of King, et al., there is shown a buildout coupling adapter system in a patch panel that makes possible interconnections among the several different types of connectors in any combination thereof. As can be seen in that patent, a buildout block at one side (or end) thereof is configured the same as a simple coupler adapter having a keyway for receiving, for example, an SC connector. The other end of the buildout block is formed to receive a buildout which may be configured to receive and hold, for example, an SC, an ST, an LC, or an FC connector. Thus, the patch panel may be, on one side thereof, pre-connectorized with optical fibers all of which are terminated by SC connectors, and the other side of the panel is ready to receive pre-connectorized fibers terminated by any one of the numerous connectors. Such an arrangement is more versatile and adaptable than those arrangements which are limited to a single type of pre-connectorized fiber. Such an arrangement also functions well in those installations where one side of the panel is not readily accessible. Thus, the panel can be pre-connectorized before mounting in position on the side which will be relatively inaccessible, after which it can be mounted in place, ready to receive the numerous connections thereto, regardless of connector type.

In any such arrangement there is a potential safety hazard that is often present. Where one or more of the pre-connectorized fibers is carrying optical energy, such energy can be emitted from the end of the fiber connector and pass through the unoccupied buildout block or coupling adapter to the side of the panel where connections are to be made. This optical energy can be harmful for the operator or installer and can be especially harmful to his or her eyes. This hazard is most prevalent when an active connection has to be repaired, cleaned, or otherwise altered by removing an existing connectorized fiber and replacing it with another. In such an instance, it might be difficult or otherwise impractical to shut off the signal transmission in that particular fiber circuit, hence, the installer is forced to deal with a light emitting junction or connection.

This hazard has long been recognized and there are numerous arrangements in the prior art for blocking any light emanating from a fiber connection through an open adapter. In U.S. Pat. No. 5,678,268 of Stephenson, et al., there is shown a pivotable optical shutter arrangement wherein a normally closed pivotable shutter blocks the open exit of an adapter when a connector plug is removed. The shutter advantageously requires only one motion to open it to permit insertion of a plug or connector into the adapter. Such a shutter as shown in the patent is operable by only one hand instead of prior art arrangements which generally require awkward use of two hands by the installer. One of the disadvantages of any shutter arrangement however, is that they are easily “defeatable” in that they can be, during installation of large numbers of connectors and in the interest of expedition, for example, temporarily fixed in the open position, thus contravening their purpose. In addition, the fiber optic transmission art has progressed to the use of higher and higher light energy or power, and has reached a point where shutter arrangements in general have, because of the large light energy, become transparent to much of that energy in the form of infra-red light, which is commonly used. Additionally, when the light intensity is very high, actual damage to the optical connector and the associated fibers can occur.

SUMMARY OF THE INVENTION

The present invention is an optical fiber connector adapter assembly wherein the adapter has a sensing mechanism comprising a switching arrangement incorporated therein for signaling associated circuitry to cut off the emission from the light source that supplies the connector plug remaining in the adapter when the first plug is removed. As a consequence, the cessation of light energy emanating from the open receptacle of the adapter assembly is complete, not subject to easy defeat, and eliminates or at least reduces the possibility of damage to the connection, fibers, and users. As will be apparent hereinafter, in some embodiments of the invention, an impending disconnect or connect is signaled, thereby eliminating possible injury to the installer during extraction of the first plug.

In a first illustrative embodiment of the invention, an adapter has first and second leaf springs extending into the plug receiving opening and positional to be pressed into contact with each other when a first plug is inserted into the adapter. The springs are attached to a suitable external circuit, such as a circuit board mounted on or adjacent the adapter, which, upon contact with each other by the leaf springs produces a control signal for turning on the light source, e.g., laser, connected to the second plug already in the adapter. Conversely, when the first plug is removed from the adapter, the circuit is broken and the laser to the second plug is turned off. Thus, the two leaf springs function as a safety switch to prevent light from emanating from an open adapter.

In a second illustrative embodiment of the invention, a light emitting device, such as an LED is mounted in one side wall of the adapter and a light detector in the opposite wall thereof. Thus, light, such as a beam, from the LED directed across the plug receiving portion of the adapter to the detector is detected thereby, in the absence of a first plug, and causes a signal to be directed to a suitable control circuit to prevent the light which normally is directed to a second plug from reaching the adapter generally by extinguishing the laser. When the first plug is inserted into the adapter, it blocks the light path between the LED and detector and the control signal circuit is broken, thereby allowing the laser to the second plug to be turned on.

In still another embodiment of the invention, a Hall effect device, which detects the presence of a magnetic field, is mounted in the adapter on, for example, an end wall thereof or on a circuit board mounted on or in the adapter. In this embodiment, the first plug has a small magnet mounted on the front plug end. When the first plug is inserted into the adapter it is moved forward until it seats therein, at which point the Hall effect device detects the presence of the magnet and produces a signal which, when applied to a control circuit, permits the light (laser) supplying the second plug to be turned on. When the first plug is removed, the magnet is no longer detected and the Hall effect device no longer produces a signal. In the absence of such a signal, the control circuit turns the laser off, or otherwise prevents light from reaching the connector end of the second plug.

In the embodiments of the invention as thus far described the sensing mechanisms produces a signal, either make or break, upon the axial insertion or withdrawal of the first plug. It is often desirable, however, to produce an advance warning of the impending insertion or withdrawal to lessen possible exposure of the operator to light within the adapter while maintaining the simplicity of the foregoing embodiments.

In an embodiment for producing an advance warning, advantage is taken of the LC connector structure which has a cantilevered latching arm thereon for latching the plug to the adapter in the operative position. In order to remove the first plug from the adapter, the latching arm must be depressed to unlatch the plug and enable its removal. In this embodiment of the invention, a Hall effect device is contained in or mounted to the adapter on the outside thereof, and the latching arm has a small magnet affixed thereto near its distal end. The location of the Hall device in the adapter, which is made of a suitable plastic material, is such that it detects the presence of the magnet when the first plug is mounted in its operative position. However, when the latching arm is depressed, the magnet moves away from the Hall device to where the magnetic field thereof is no longer easily detectable and the Hall device signals the control circuit of this condition so that the control circuit shuts off the light supplied to the second plug, even though the first plug has not yet been withdrawn. Thus, the light to the second plug is shut of in anticipation off the removal of the first plug.

In another embodiment for producing an advance warning, a cantilevered leaf spring contact is disposed in the region of the adapter in which the cantilevered latching arm resides when the plug is inserted therein, and a contact pin is affixed within the region adjacent the latching shoulder. When the plug is inserted into the adapter, the latching arm is depressed until the latching lugs or shoulders thereon pair the latching shoulder in the adapter, at which time the arm springs up to engage the latch and the latching lugs and arm force the leaf spring into contact with the contact pin, completing the circuit. When the plug is to be removed, it is necessary that the latching arm first be depressed, breaking the circuit as the latch or latches are disengaged, at which point the latching lugs no longer bear against the leaf spring and it disengages from the contact to break the circuit which the plug is still within the adapter.

In still another embodiment of the invention, use is made of the shutter arrangement of the previously mentioned U.S. Pat. No. 5,678,268. Each sidewall of the pivotable shutter has a depending leg near the distal end of one of which is a light emitting device, e.g. an LED, and the distal end of the other of which is a light detecting device. When the shutter is closed, i.e., there being no first plug in the adapter, the light circuit is completed and the power to the second plug is disabled. However, when the shutter is pivoted upward, the circuit is broken and power to the second plug is resumed. In the '268 patent, it is shown how pivoting the shutter upward is a function of the plug itself, thus the plug is at least partially inserted before power to the second plug is resumed, thereby protecting the operator. On the other hand, as the first plug is withdrawn, the locations of the LED and detector are such that the power to the second plug is cut off before the first plug is fully withdrawn.

The various principles and features of the present invention are, as will be seen hereinafter, adaptable to numerous other arrangements. While the safety aspects of the present invention are of paramount importance and are treated in detail, the switching capability of the adapter might readily be adapted for other uses that might occur to workers in the art. These principles and features and the advantages thereof will be more readily apparent from the following detailed description, read in conjunction with the accompanying drawings.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a quadraplex adapter and two connector plugs as presently used in the prior art;

FIG. 2 is a side elevation view in cross-section of connector plugs and an adapter assembly as presently used in the prior art;

FIG. 3 is a side elevation view in cross-section of a portion of a simplex adapter assembly of a first embodiment of the present invention;

FIG. 4 is a front elevation view in cross-section along the line A—A of the adapter assembly of FIG. 3;

FIG. 5 is a diagrammatic view of a circuit arrangement for use with the adapter assembly of FIGS. 3 and 4, and with subsequent embodiments of the present invention;

FIG. 6 is a perspective view of a second adapter assembly embodying the principles of the present invention;

FIG. 7 is a front elevation view of the adapter assembly of FIG. 6;

FIG. 8 is a plan view of the adapter assembly of FIGS. 6 and 7 in cross-section along the line A—A of FIG. 7;

FIG. 9 is a side elevation view in cross-section of a portion of a third adapter assembly embodying the principles of the present invention;

FIG. 10 is a front elevation view of the adapter assembly in cross-section along the line A—A of FIG. 9;

FIG. 11 is a side elevation view of a connector plug for use with the adapter assembly of FIGS. 9 and 10;

FIG. 12 is a plan view and schematic diagram of a circuit board for use with the adapter assembly of FIGS. 9 and 10;

FIG. 13 is a perspective view of still another adapter assembly and connector plug embodying the principles of the present invention;

FIG. 14 is a side elevation view of an adapter assembly embodying the principles of the present invention wherein the adapter assembly has a pivotable shutter;

FIG. 15 is a front elevation view of the adapter assembly in cross-section along the line A—A of FIG. 14;

FIG. 16 is a side elevation view of the adapter assembly of FIGS. 14 and 15 with a connector plug partially inserted therein;

FIG. 17 is a side elevation view in partial cross-section of the adapter and plug depicting the disconnect position of a leaf switch in the adapter;

FIG. 18 is a side elevation view in partial cross section of the adapter of FIG. 17 with the plug fully inserted therein; and

FIG. 19 is a front elevation cross-sectional view along the line A—A of FIG. 17.

DETAILED DESCRIPTION

FIG. 1 is a perspective view of a quadruplex jack receptacle or adapter 11 mounted on a panel 12 and locked thereto by locking members 13. Adapter 11 is made of suitable plastic material and members 13 are molded into the top and bottom surfaces 14 and 16 respectively. An optical connector 17 of, for example, the LC type is shown mounted in one of the four rectangular cavities 25 of the adapter 11, and a similar connector 18 is shown positioned for insertion into another of the cavities 25 thereof. Each connector comprises a housing 19 and cover 21 that enclose fiber holding structure. Connector 17 has a bend limiting boot 22 and terminates a cable 23. In like manner, connector 18 also terminates a cable, not shown. Both connectors 17 and 18 include a plug end 20 which is insertable in one of the cavities of adapter 11. As best seen with connector 18, each connector includes latching tab or arm 24, molded as part of connector 18, which serves to lock the connector within its receptacle, the cavity. Arm 24 includes a “living hinge” which allows it to be moved up and down relative to the central axis of the connector. Arm 24 has first and second protruding latching lugs or shoulders 9 which, when plug or connector 17 is fully inserted within adapter 11, mate with latching surfaces 10 of stop members 8 within the adapter. In order for the latch to be disengaged so that plug 17 may be removed, latching arm 24 must be depressed to where latching lugs 9 no longer engage surface 10. A trigger 26 is also molded as part of the connector and has a free end overlying the distal end of arm 24. Trigger 26 has a “living hinge” and when its distal or free end is depressed, it depresses the distal end of arm 24 to unlatch the connector 18 from the adapter (or jack receptacle) 11. It is to be understood that the adapter and connection shown in FIG. 1 are intended to be representative of several different types of connectors and adapters therefor, as is the assembly shown in FIG. 2.

FIG. 2 is a cross-sectional view of the arrangement of FIG. 1, and shows a second, mating adapter 11 which mates with the adapter 11 of FIG. 1, each of the adapters having mating flanges 27 which form, or are extensions of, end walls 28 of the adapters 11. Each end wall 28 has a protruding cylindrical member 29 having a bore therein, which, when the adapters are mated aligns with a corresponding bore in the other adapter. The two aligned bores contain an alignment sleeve 31 into which the optical fiber containing ferrules 32 of the two connectors 17 are inserted in butting relationship. When fully inserted in the mated adapters 11, the ends of ferrules 32 are maintained in abutment by means of springs 33, for example. When in this configuration, optical energy is transmitted from one connector to the other with minimized loss. It can be seen from FIG. 2 that if the right hand connector 17, as viewed in FIG. 2, is removed, light energy in the left hand connector 17 will be directed through the now empty cavity 25 of the right hand adapter 11 in an unimpeded path. As discussed hereinbefore, this creates a hazardous condition, especially when the transmitted light is high intensity or power.

FIGS. 3 and 4 depict a first embodiment of the present invention which is directed to minimizing or eliminating the hazardous condition described in the foregoing. FIG. 3 is a partial view in cross-section of that portion of the connector assembly of FIG. 2 involving the region of abutment of the connector ferrules 32 and FIG. 4 is a cross-sectional elevation view taken along the line A—A of FIG. 3. As best seen in FIG. 3, a first leaf spring 36 of, for example, beryllium copper, is mounted to flange 27 and extends into the rectangular cavity 25, preferably bearing against wall 28. As seen in FIG. 4, spring 36 is positioned between cylindrical member 29 and a side wall 37 of the adapter 11. Spring 36 may be molded into the adapter 11, or it may be riveted or otherwise mounted to flange 27. A second spring 38 extends from an opposite wall of adapter 11, substantially parallel to and overlying spring 36 with a small separation therebetween as best seen in FIG. 3 thereby forming a normally open leaf spring switch. A first electrical lead 39 is connected to the proximal end 41 of spring 36, and a second electrical lead 42 is connected to the proximal end 43. When a plug 17 is inserted into the rectangular cavity 25 it is advanced until latching arm 24 latches it to the adapter. As shown in FIG. 2, the plug end 20, in this position, surrounds cylindrical member 29 and penetrates to a point closely adjacent end wall 28, and, as a consequence, depresses second spring member 38 into contact with spring member 36, thereby completing an electrical connection between leads 39 and 42. Thus, the combination of springs 36 and 38 function as a switch, or, more generically, as a sensing mechanism which registers the presence of a fully inserted connector 17 within adapter 11.

FIG. 5 is a diagrammatic view of the system 46 of the present invention, showing the mating adapters 11 mounted to the panel 12, with a first connector plug 47 about to be inserted into an adapter 11 to mate with (abut) a second connector plug 48 positioned and latched into its adapter 11. Connector plug 48 is shown supplied with an optical input from, for example, a laser 49, hence in the arrangement shown, connector 48 is “live” when laser 49 is on. Leads 39 and 42 lead to a control circuit 51 which, when the spring contacts 36 and 38 are not in contact, thereby forming an open switch, circuit 51 generates a control signal which is applied to laser 49 through a suitable connection 52 to, for example, a switch 53 on laser 49 to maintain it in the unenergized, or off, state. When the second plug connector 47 is inserted into its adapter 11 until seated therein, spring members 36 and 38 are pressed into contact with each other, as explained hereinbefore, and the circuit to control member 51 is closed. Control member 51 then generates an “on” signal which is applied to switch 53 to turn the laser 49 on so that normal signal transmission can occur. From the foregoing, it can be appreciated that the switch formed by the springs 36 and 38 functions as a sensing mechanism for sensing the presence or absence of a plug connector in the adapter, and signaling other circuit elements accordingly The operator or installer is thus protected from the harmful effects of laser light emerging unimpeded from an unoccupied opening or receptacle in the adapter. Control element 51 can take any of a number of forms, the design of which are well within the purview of workers in the art and, where the arrangement calls for a voltage source, element 51 can so function. In addition, it is possible to eliminate the control circuit 51 and apply a signal directly to the light source 49 in certain circumstances. In the arrangement of FIG. 5, it is understood that the sensing mechanism formed by the leaf springs 36 and 38 is part of a circuit within control circuit 51 including a voltage (or current) source which is part of the signal generating mechanism activated upon closure of the switch formed by leaf springs 36 and 38.

FIG. 6 is a perspective view of another embodiment of the invention, of which FIG. 7 is a front elevation view and FIG. 8 is a plan view in cross-section along the line A—A of FIG. 7. To avoid confusion, parts in these figures that correspond to like parts in preceding figures bear the same reference numerals.

FIG. 6 depicts first and second mated adapters 56 and 57. Mounted in diametrically opposed openings in side walls 58 and 59 of adapter 56 are a light source 61, such as, for example, an LED, and a light detector 62 preferably directly opposite source 61. Lead 39 which can actually be more than one wire connects the light source 61 to the control circuit 51 which supplies the necessary power thereto, and lead 42 which can also be, if necessary, more than one wire, connects the detector 62 to the control circuit. As best seen in FIG. 8, in the absence of a plug connector in the receptacle 63 of adapter 56, light from source 61 impinges on detector 62, thereby providing an indication of the absence of a connector to control circuit 51, which thereupon generates a control signal to turn laser 49 off. When a plug connector is inserted into receptacle 63, the light beam from source 61 to detector 62 is interrupted, and detector 62 does not send a light indicating signal to circuit 51. In the absence of such a signal, the laser 49 is switched on and normal operation of the connection obtained. In the embodiment of FIGS. 3 and 4, insertion of a plug connector into the adapter completed a circuit to the control circuit 51, but in the arrangement of FIGS. 6, 7, and 8, insertion of a plug connector into the adapter, breaks a circuit of which the light beam is a part. Thus, control circuit 51 is, in the first instance, programmed to turn the laser on, and, in the second instance, to turn the laser off. It is a simple matter to produce the necessary circuitry in circuit 51 to accomplish the desired response to insertion and removal of a plug connector relative to the adapter.

FIGS. 9, 10, 11, and 12 depict an embodiment of the device which makes use of a Hall effect device as the sensing mechanism. Elements in these figures that correspond to elements in FIGS. 3 and 4 bear the same reference numerals.

In FIG. 9, it can be seen that flanges 27 have a slot 66 cut therein at their junction which contains a circuit board 67 which extends into adapter 11 to the cylindrical member 29. As seen in FIG. 12, board 67 has a Hall Effect device 68 mounted on the lower portion thereof. As is known, such a Hall Effect device detects the presence of a magnetic field. To this end, connector plug 17 has mounted on its front end 20 a small magnet 69. When the plug 17 is inserted into the adapter 11 until it is seated, as shown in dashed lines in FIG. 9, the magnet 69 is immediately adjacent the Hall device 68, which detects its magnetic field. With reference to FIG. 12, the Hall device 68, which is biased by a voltage V₊, which is applied thereto by lead 71 from a suitable voltage source, which can be, for example, control circuit 51, when it detects a magnetic field, causes a transistor 72 to be activated. Transistor 72 is biased by voltage V₊ over lead 73 and resistor 74, and generates an output signal over lead 76 which is applied to control circuit 51. Circuit 51 in turn, turns on laser switch 53 to activate laser 49. When connector plug 17 is removed, by depressing latching arm 24 and pulling it out of opening 25, as the magnet 29 moves away from reusing member (the Hall device 68) its magnetic field is no longer detected in sufficient strength to activate transistor 72, whereby the signal to control circuit 51 ceases and circuit 51 turns laser 49 off by deactivating switch 53. It is to be understood that the circuit arrangement shown in FIG. 12 is representative of any of a number of possible circuits for accomplishing the foregoing operation which are within the purview of workers in the art. From the foregoing it can be seen that the Hall device senses the presence (or absence) of a connector plug relative to adapter 11 and insures that unimpeded laser light will not be emitted through an empty or unoccupied adapter 11.

FIG. 13 is a perspective view of a variation of the arrangement of FIGS. 9 through 12 wherein the sensing mechanism comprises the circuit board 67 containing the Hall Effect device 68 mounted in a side wall 77 of adapter 11 with device 68 preferably being flush with the inner surface of wall 77. Mounted on or in the latching arm 24 is a magnet 78 which, when connector plug 17 is fully seated within adapter 11 is immediately adjacent the Hall device 68 for detection of its magnetic field and thus signaling control circuit 51 of its presence in the adapter 11 in the manner explained hereinbefore. When connector plug 17 is removed from the adapter 11, latching arm 24 is depressed, thereby moving magnet 78 away from the Hall device 68 a distance sufficient to where its magnetic field is no longer detectable by the Hall device 68, which results in laser 49 being deactivated before connector plug 17 is removed. This arrangement signals the impending removal of the connector plug 17 and the laser 49 is deactivated before the plug 17 is fully withdrawn. Thus, the arrangement of FIG. 13 has the additional safety feature of deactivation of the laser 49 while the plug 17 is still within adapter 11, but while it is being removed.

FIGS. 14, 15, and 16 are views of still another embodiment of the invention, which represents a modification of the optical shutter arrangement of U.S. Pat. No. 5,687,268 of Stephenson et al., which also incorporates the additional safety feature of advance warning to the control circuit 51 that a connector plug is about to be inserted into, or removed from the adapter 11.

The embodiment of these figures comprises an adapter assembly 18 which, as shown in FIGS. 14 and 15 has an adapter 82 which has an empty receptacle, and a pivotable shutter 83 which covers the opening of the receptacle, as shown. Shutter 83 is pivoted on pivot pin 84 to the position shown in FIG. 16 when a connector plug 85 is inserted in the receptacle of adapter 82. Shutter 83 also has a flange member 86 for pivoting shutter 83 by means of connector plug 85 when the plug is being inserted into adapter 82, as explained in detail in the aforementioned Stephenson et al. '268 patent. Shutters 83 has first and second depending arms 87 and 88 which extend below the lower surface of adapter 82, as shown in FIG. 14 and in FIG. 15 which is an elevation view in cross-section along the line A—A of FIG. 14. At the distal end of arm 87 is mounted a light emitting device 89 such as an LED, and the distal end of arm 88 has a light detecting device 91 for detecting light emitted from device 89, as shown in FIG. 15. Thus, when there is no connector in adapter assembly 81, more specifically, in adapter 82, the shutter member 83 is closed and, ordinarily, light is blocked from exiting adapter 82, and light emitted from device 89 is detected by device 91, which signals control circuit 51 that one receptacle of adapter 82 is empty. As a consequence, circuit 51 deactivates laser 49, as discussed hereinbefore. This additional safety measure is most useful where the signals carried in the fibers to the adapter are of high power level, as pointed out hereinbefore. When a connector plug 85 is to be inserted into adapter 82, the plug is used to pivot the shutter 83 upward toward the position shown in FIG. 16. As the shutter 83 pivots, the light path between devices 87 and 88 is interrupted and blocked by the body of adapter 82. Thus control circuit 51 no longer receives a signal from device 91, and, in response to the absence of the signal, activates laser 49. It will be apparent to those in the art that the length of arms 87 and 88 and the location thereon of device 89 and 91 can determine at which point in the insertion or extraction of the connector plug the laser is activated or deactivated. Thus, the embodiment of FIGS. 14, 15, and 16 can signal the impending insertion or removal of the connector plug, thereby adding an additional increment of safety.

In FIGS. 17 and 18 there is shown another embodiment of the invention which, like the embodiment of FIG. 13, signals the impending removal of the connector plug 17 from the adapter 11. As can best be seen in FIG. 17, a cantilevered leaf spring 96, which may be made of suitable conducting material having a high degree of spring to it, such as beryllium copper, is mounted in suitable fashion in adapter 11. The mounting arrangement shown is intended to represent any of a number of possible mounting arrangements which position the cantilevered leg of spring 96 in the region of space 25 that accommodates the latching arm 24 of connector plug 17, with the tip 97 thereof almost aligned with latching surface 10. It is preferable that tip 97 be positioned as shown so that it does not interfere with either plug 17 or latching arm 24 as plug 17 is inserted into adapter 11. At the comer formed by latching surfaces 10 and the wall, and extending above the tip 97 and spaced therefrom is a fixed conductive contact member 98. Leads 99 and 101 are connected to spring 96 and contact 98, respectively.

As can be seen in FIG. 19, spring 96 is substantially equal to the slot 102 which contains latching arm 24 when plug 17 is fully inserted in adapter 11, and contact 98 bridges the gap, as shown. Spring member 96 can be, if desired, wider than is shown, since it is not contained in slot 102, and there is ample room within adapter 11 for a wider cantilevered spring 96. It is also possible, if desired, to offset spring 96 from the centerline of adapter 11.

As best seen in FIGS. 17 and 18, when connector plug 17 is being inserted into adapter 11, latching arm 24 is depressed, initially by the operator and then by the downward camming action of members 8 bearing against latching lugs 9. As a consequence, initially latching arm 24 does not engage end 97 of spring 96, and the electrical circuit remains open, thereby reducing the hazard of laser light escaping through adapter 11, as discussed hereinbefore. As lugs 9 pass the surfaces 10 and they are no longer held down by the camming action of the bottom surfaces of stop member 8, the resilience of arm 24 causes it to spring upward to bring the lugs 9 to bear against surfaces 10. At the same time, the arm 24 and lugs 9 engage the end 97 of spring 96 and force it into electrical contact with contact member 98, closing the electrical circuit and turning the laser on. The embodiment of FIGS. 17, 18, and 19 therefore represent a virtually completely safe arrangement. Without a plug 17 being inserted in adapter 11, the laser is off and the operator or installer is protected from any potentially harmful radiation. The laser is not turned only until the plug 17 is fully inserted and the latches seated or matched. When the plug 17 is to be withdrawn, depression of arm 24 is a necessary first step in unlatching plug 17 from adapter 11, and such depression of arm 24 turns off the laser by breaking the circuit. Thus, the operator or installer is substantially completely protected since the laser is only on when the plug is fully inserted.

In the several embodiments of the invention herein discussed, the adapter assembly of the invention has incorporated therein a sensing mechanism which signals the presence or absence of a connector plug in the adapter, and, further, in some of the embodiments, the impending removal or insertion of such plug. While the emphasis herein is on safety, it will be obvious that such information might be useful for other purposes not herein discussed. Additionally, other configurations of the sensing mechanism besides those disclosed might occur to workers in the art. It is to be understood that the various features of the present invention might be incorporated into other types of connector adapters and that other modifications or adaptations might occur to workers in the art. All such variations and modifications are intended to be included herein as being within the scope of the present invention as set forth. Further, in the claims hereinafter, the corresponding structures, materials, acts and equivalents of all means or step-plus-function elements are intended to include any structure, materials, or acts for performing the functions in combination with other elements as specifically claimed. 

We claim:
 1. An optical fiber coupling adapter assembly comprising: an adapter housing having a receptacle therein for receiving a connector plug having a ferrule extending from its front end and a latching arm; said adapter having a latching surface within said receptacle which latches the connector in place when said surface is engaged by the latching arm; said adapter having a sensing means therein for sensing when said surface is so engaged by the latching arm and producing an indication of the latched condition; and said sensing means being positioned to respond to an unlatching of the latching arm in said receptacle prior to withdrawal of the connecter plug for producing an indication of the unlatched condition prior to such plug withdrawal.
 2. An optical fiber coupling adapter as claimed in claim 1 wherein said receptacle has an open end, and said sensing mechanism comprises a cantilevered leaf spring having a distal end and having an end thereof affixed to said adapter and extending toward said open end to its distal end; a contact member affixed to said adapter adjacent the distal end and spaced therefrom a distance sufficient to be contacted by said distal end when said leaf spring is flexed by the connector plug when it is substantially fully inserted into said adapter.
 3. An optical fiber coupling adapter assembly as claimed in claim 1 wherein said securing means comprises a cantilevered spring member in said receptacle and an electrical contact member adjacent said latching surface, said spring member being positioned to be moved into engagement with said contact member by the connector plug latching arm when the latching arm engages said latching surface.
 4. an optical fiber connector assembly comprising: a connector plug; a connector adapter forming a receptacle for said connector plug for receiving and latching said plug therein, and said receptacle having first and second side walls; said connector plug having a latching arm thereon having a latched position within said receptacle and an unlatched position therein; a mechanism for sensing the particular latched or unlatched position of said latching arm and producing a signal indicative of the latched or unlatched position of said connector plug.
 5. An optical fiber connector assembly as claimed in claim 4 wherein said latching arm has at least one latching lug thereon sand said receptacle has a latching surface therein against which said latching lug bears in the latched position of said connector plug.
 6. An optical fiber connector assembly as claimed in claim 5 wherein said sensing means comprises a spring member in said receptacle and an electrical contact member adjacent said latching surface; said spring member being positioned to engage said contact member when said latching lug engages said latching surface.
 7. An optical fiber connector assembly as claimed in claim 6 wherein said spring member is a cantilevered leaf spring having a distal end positioned to be engaged by said latching lug and forced against said contact member when said latching lug bears against said latching surface.
 8. An optical fiber connector assembly as claimed in claim 5 wherein said sensing means comprises a magnetic field detecting device mounted in one of said side walls of said receptacle; and said latching arm has a magnetic member mounted therein, said magnetic member being adjacent said magnetic field detecting device when said latching arm is in said latched position and removed from said magnetic field detecting device when said latching arm is in its unlatched position.
 9. An optical fiber connector assembly comprising a connector plug and a connector receptacle for receiving and latching said plug whereby said plug has a latched or an unlatched condition within said receptacle, said receptacle having a light transmitting member connected thereto and to a control circuit and a light source, said assembly further comprising: a sensing mechanism in said receptacle for sensing the particular condition signifying the presence or absence of a latched plug for producing a signal indicative of at least one of said conditions; a movable member on said connector plug for activating said sensing mechanism in response to the latched condition of said plug; and said signal being applied to said control circuit to activate said light source when said plug is latched in said receptacle.
 10. An optical fiber connector assembly as claimed in claim 9 wherein said movable member on said connector comprises a latching arm.
 11. An optical fiber connector assembly as claimed in claim 10 wherein said latching arm is a cantilevered resilient member wherein depression thereof unlatches said plug and de-activates said sensing mechanism. 